1. Field of the Invention
The present invention relates generally to an electric power supplying apparatus, and more particularly, to an apparatus for supplying a load, such as a secondary battery, a condenser for accumulating electric power and so on, with electric power generated by a generator which has a rotor driven to rotate by a manual rotary driver.
2. Description of the Prior Art
There has been proposed an electronic equipment, such as a portable radio receiver or the like, which is provided with a manual rotary driver and a generator having a rotor and operative to generate electric power when the rotor is driven to rotate by the manual rotary driver. When such an electronic equipment is put into actual use, for example, the manual rotary driver is rotated manually by a user to drive the rotor of the generator to rotate, so that the generator is put to operation for generating electric power. The electric power obtained from the generator is supplied to a secondary battery or a condenser for accumulating electric power, such as an electrical double layer condenser, connected with the generator as a load. The electronic equipment, such as the portable radio receiver or the like, is operative to work with a power source of the secondary battery or the condenser for accumulating electric power in which the electric power from the generator is stored or accumulated.
Since such an electronic equipment containing the generator as mentioned above generates electric power for itself as occasion demands, it can be put into operation without any external power source and without being concerned about consumption of a battery contained therein. Accordingly, it is spontaneously considered that the electronic equipment containing the generator is used for countermeasures against various calamities. For example, under a situation where a commercial electric power supplying system is visited by a calamity, such as a big earthquake, a big fire and so on, and an inconvenience in which it is very difficult to obtain new batteries is raised by the calamity, the electronic equipment containing the generator can be operative to function normally.
Consequently, it is required for the electronic equipment containing the generator to be made portable and easily carried and used with simple operations by a user when a calamity occurs. It is further desirable that the generator contained in the electronic equipment, the manual rotary driver for driving the rotor of the electronic equipment to rotate and a portion for supplying a load provided to the generator with electric power is miniaturized in weight and size so that high efficiency is obtained.
Under such circumstances, a previously proposed electronic equipment containing a generator, for example, a radio receiver containing a generator comprises a direct-current generator, a rotary driving mechanism which can be rotated manually, and an accelerating mechanism for increasing the rotation of the rotary driving mechanism and transmitting the increased rotation of the rotary driving mechanism to the rotor of the direct-current generator. When the rotary driving mechanism is rotated manually, the rotation of the rotary driving mechanism is increased 40 to 50 times by the accelerating mechanism and the increased rotation is transmitted to the rotor of the direct-current generator so as to cause the direct-current generator to generate electric power. The electric power obtained from the direct-current generator is directly supplied to a secondary battery to be stored in the same.
In the radio receiver containing the generator as mentioned above, when the rotary driving mechanism is rotated manually by a user, the rotation of the rotary driving mechanism is increased 40 to 50 times by the accelerating mechanism and transmitted to the rotor of the direct-current generator so as to rotate the same. In this case, since a torque necessary for rotating the rotor of the direct-current generator is relatively large usually, there has been a problem that the user who rotates manually the rotary driving mechanism is required to spend a relatively great deal of labor.
That is, an initial torque necessary for the incipient stage of the rotation of the rotor of the direct-current generator is especially increased by reason that the rotation of the rotary driving mechanism is increased 40 to 50 times by the accelerating mechanism. In addition, since the electric power obtained from the direct-current generator is directly supplied to the load, electric power required by the load is supplied from the direct-current generator in such a manner that the output voltage of the direct-current generator is arranged to be relatively low in consideration of an allowable voltage between the input terminals of the load and the output current of the direct-current generator is arranged to be relatively large. Therefore, the torque necessary for rotating the rotor of the direct-current generator becomes relatively large in response to the relatively large output current of the direct-current generator by reason of the following.
Generally, in a generator having a stator and a rotor, such as the direct-current generator mentioned above, for example, a coil wound on a magnetic core is provided on the stator and a permanent magnet opposite to the magnetic core on which the coil is wound is provided on the rotor. When the permanent magnet provided on the rotor is moved relative to the magnetic core on which the coil is wound, electro motive force is generated in the coil and a current based on the electro motive force flows through the coil to form an output current of the generator on condition that a load is connected with the generator. When the current flows through the coil, the magnetic core on which the coil is wound is magnetized by that current, so that magnetic attractive force and magnetic repulsive force are generated between the magnetic core and the permanent magnet provided on the rotor an electro-magnetic brake acts on the rotor. Accordingly, a torque overcoming the electro-magnetic brake acting on the rotor is necessitated to rotate the rotor. The larger the current flowing through the coil wound on the magnetic core, namely, the output current of the generator is, the larger the electro-magnetic brake acting on the rotor becomes. Consequently, the larger the output current of the generator is, the larger the torque necessary for rotating the rotor becomes.
Besides, in the direct-current generator, since the polarity of the output voltage depends on the direction of rotation of the rotor, it is required for the rotary driving mechanism to be accompanied with a device for preventing the rotor from rotating reversely. This results in that the structure of the rotary driving mechanism is complicated.
Further, in the direct-current generator, since the electric power is obtained through a switching rectification by brush elements, noises in generation result from the switching rectification. Therefore, when the radio receiver containing the direct-current generator is put to operation for receiving a radio broadcasting signal under a condition in which the direct-current generator is operating to generate electric power, undesirable noises are mixed in a reproduction output from the radio receiver.